1. Field of the Invention
The invention relates to a drilling implement with a derrick or mast, a drill drive guided on said derrick or mast for driving a drill rod and a gearing placed between the drill drive and drill rod for transmission purposes.
2. Description of related art including information disclosed under 37 CFR §§1.97 and 1.98
Frequently with such a drilling implement different drilling methods are to be carried out or during a complex drilling procedure different demands are made on the rotation speed and/or torque of the drill or drill rod respectively.
One possibility for meeting these different demands consists of using different drilling implements. However, in the case of complex drilling procedures this involves a considerable expenditure, because e.g. successive drilling steps have to be carried out with different drilling implements.
Thus, e.g. with known drilling implements the rotation speed of a drill drive can be regulated or controlled. Thus, even with a single drilling implement it is possible to implement different rotation speeds and torques on the drill rod or drill respectively. However, this suffers from the disadvantage of the relatively high constructional expenditure for the motor and the complex control. Thus, such a drilling implement is associated with comparatively high manufacturing and maintenance costs. A drilling implement with a regulatable drill drive is described in JP 8-226372. JP 07-076984 describes the use of hydraulic motors having two speeds and an additional change in the hydraulic drive of the motors from series to parallel connection.
As an alternative drilling implements with shiftable gears have been proposed. Said gears generally have a relatively complex construction. A drilling implement with an adaptable gear ratio between the drill drive and drill rod is e.g. known from JP 2002-97882. In order to provide different rotation speeds and torques on the drill rod said specification proposes the provision of two different gear ratio stages, which can be used as desired.
The known drilling implements allowing an adaptation of the rotation speed of the drill rod either have a complex drive or a complex gear.